Device for displacing and replacing a specimen in vacuum-tight analysis equipment

ABSTRACT

IN A VACUUM TIGHT ANALYSIS EQUIPMENT, THE MECHANISM USED FOR VARYING THE POSITION OF THE STAGE WITH A VIEW TO VARYINGL THE ANALYZED PORTION OF THE SYSTEM ALSO MAKES IT POSSIBLE TO POSITION THIS STAGE OPPOSITE THE INTERNAL OPENING THROUGH WHICH THE SPECIMEN CHAMBER COMMUNICATES WITH THE AIR-LOCK   CHAMBER. AN AUXILIARY MECHANISM THEREAFTER IMPARTS TO THE STAGE A TRANSLATION MOVEMENT AT THE END OF WHICH THIS INTERNAL APERTURE IS OBTURATED BY THE STAGE AFTER A SPECIMEN FIXED THERETO HAS PENETRATED INTO THE AIR-LOCK CHAMBER.

United States Patent [32] Priority Aug. 14, I968 [33] France [31] 162,990

[54] DEVICE FOR DISPLACING AND REPLACING A SPECIMEN IN VACUUM-TIGHT ANALYSIS [50] Field of Search 2l4/l7.4; 250/495 (2) [5 6] References Cited UNITED STATES PATENTS 2.602.899 7/1952 Page 250/52X 3,150,259 9/1964 Wilska 250/495 Primary Examiner-Robert G. Sheridan AlmrneyCushman, Darby & Cushman ABSTRACT: In a vacuumtight analysis equipment, the mechanism used for varying the position of the stage with a view to varying the analyzed portion of the system also makes it possible to position this stage opposite the internal opening E through which the specimen chamber communicates with the aims rawmg air-lock chamber. An auxiliary mechanism thereafter imparts [52] US. Cl 214/17, to the stage a translation movement at the end of which this in- 250/495 ternal aperture is obturated by the stage after a specimen fixed [5 l 1 Int. Cl H0 lj 31/26 thereto has penetrated into the air-lock chamber.

PATENTED JUN28 I97i SHEET 2 BF 2 DEVICE FOR DISPLACING AND REPLACING A SPECIMEN IN VACUUM-TIGHT ANALYSIS EQUIPMENT The present invention relates to an improvement in equipments, such as electron-microscopes or ion microanalyzers of the kind in which a specimen is analyzed inside an evacuated enclosure.

According to the invention, there is provided a device for the displacement and replacement of the specimen in a specimen chamber, said device comprising: a stage having a center part for supporting a specimen and a peripheral part; an air-lock chamber having a wall provided with an aperture having edges, said air-lock chamber communicating with said specimen chamber through said aperture; a first mechanism giving to said stage 2 freedom, in said specimen chamber, within a space portion allowing the analysis of various zones of a specimen fixed thereto, said first mechanism making it further possible to place said stage opposite said aperture in a predetermined position outside said space portion; and an auxiliary mechanism for imparting to said stage a translatory movement between said predetermined position and a further position in which said peripheral part of said stage abuts said edges of said aperture, whereby said aperture is obturated after a specimen fixed to said stage has penetrated into said air-lock chamber.

The device in accordance with the invention has the advantages of being relatively simple compared with the known devices. In a preferred embodiment, it avoids the need for any control arrangements involving vacuumtight rotating or sliding joints and can easily be connected, if required, to an automatic system.

The invention will be better understood, and other ofits features rendered apparent, from a consideration of the ensuing description and the related drawings in which:

FIGS. 1 and 2illustrate respectively in vertical section along the axes xx, xx' of FIG. 2 and in horizontal section along the axis y of FIG. I, a specimen compartment equipped with a device in accordance with the invention, the movable parts of the device occupying different positions in the two figures, the specimen being in the analysis position in FIG. 1 and in the air lock chamber in FIG. 2; and

FIGS. 3 and 4 are schematic views of details of the device of FIGS. I and 2.

In FIGS. I and 2, the reference 50 indicates that part of the evacuated enclosure which delimits the specimen chamber of an ion microanalyzer. This enclosure is extended in the form in a tubular section 51 penetrating partially into the chamber 50. The remainder of the enclosure has been indicated only roughly in FIG. 2.

The axis x'x' (FIG. 2), y (FIG. I) of the tubular section SI, is the axis ofthe apparatus."

The chamber 50 contains a stage comprising a platform 1 at the center of which the specimen E can be fixed by means of claws 2. When the stage and the components secured to it are in a position such that the axis of the stage coincides with that of the apparatus (FIG. I), or very nearly so, the specimen can be bombarded by a beam of primary ions produced by the gun 53 (FIG. 2). The secondary ions emitted from the specimen are then focused in the tubular section 51 by means of an ionoptical device 54, having the same axis as the apparatus.

The stage has an extension in the form of a slide 55, coaxial therewith, which can slide within a guide 52 against which the platform 1 of the stage is applied by the action of a return spring 58 in the absence of any force exerted on the free end of the slide.

The guide 52 is secured to a slide 5 perpendicular to the slide 55. The slide 5 can slide within a guide 66 extending through an aperture formed in the wall 50 and a further aperture, formed in a support 28 which closes this wall. The guide 66 is secured to a rocking cradle 3 fitted with a spindle 4 and a journal 40, which are journaled in bearings carried by the support 28 outside the evacuated enclosure and on which the cradle can thus oscillate, the oscillation axis being parallel to the axis of the apparatus but not being in the same vertical plane.

The spindle 4, also drives a rocker 8 having two arms extending normally to the spindle.

A metal bellows 6, is mounted between the periphery of the opening formed in the support 28 and a collar 67 provided on the slide 5. The bellows which can be both bent and compressed, serves to seal off the specimen chamber.

The lower arm of the rocker 8, carries a manual control lock 7, loaded by a spring and which can swing between two stable positions A and B relatively to said arm, this lock being shown in FIG. I.

The angular position of the spindle 4 is defined by the angle 0 made by the axis of the slide 5 with the vertical plane containing the axis of the spindle 4. When 0 is' equal .to a predetermined value 0,,, the axis 14 of the slide 5 intersects the axis y of the apparatus, as shown in FIG. 3, the latter being a schematic view in a vertical plane normal to the spindle 4. It is then possible, by means of the slide 5, to adjust the distance R between the axis of the spindle 4 and the axis of the stage to a value R, such that the axes of the apparatus and the stage coincide in the manner indicated in FIG. 3.

Variations by iAR/Z about R,,, and by i-AO/Z about 0,, make it possible to bring any desired zone of the specimen onto the axis of the equipment.

An air-lock chamber 30 (FIG. 2) is provided with an external aperture which may be obturated by a port 9 and communicates with the specimen chamber through a circular aperture provided in their common wall; the axis s of this internal aperture is shown in F IG. 3.

For R=R and 0=0,, the axis of the internal aperture of the air-lock chamber 30 and the axis of the stage coincide.

When the spindle 4 is positioned to give said value 6,, with R=R,,, the slide 55 (FIG. 2) is positioned opposite a thrust pin 20 which is slidably mounted in a guide formed in the wall of the chamber 50 and penetrating into the same through an orifice which is sealed off by a metal bellows 71.

The pin 20 displaces the slide 55, and under its action the object E penetrates into the air-lock chamber. The platform 1 runs then against the periphery of the internal opening of the air-lock chamber and closes the latter. This closure is made airtight by means of an airtightjoint 11 carried by the platform I.

When no pressure is any longer exerted by the pin 20 on the slide 55, the platform runs under the action of the spring 58 against the guide 52.

The stage can then be brought again in the working position for performing the analysis.

To sum it up, the displacements of the stage respectively corresponding to its 3 of freedom are respectively controlled:

a. by the rocking of the spindle 4;

b. by the sliding of the slide 5 within the guide 66;

c. by the sliding of the slide 55 within the guide 52, provided angle 6 is made equal to 0,, and distance R is made equal to R Those displacements in turn can be controlled in any desired way.

Preferably, however, the angular position of the spindle 4, within the angular sector A6, is controlled by a motor MAO, the shaft of which, when the lock 7 is in the position A, is connected to the spindle 4 through a conventional mechanical coupling comprising a gear 62 and a toothed sector 63, the left-hand part of the lock 7 engaging, in position A, in a notch of said sector.

On the other hand, when the lock 7 is in position B, its righthand extremity engages in a notch provided in the bearing support 28 which is integral with the wall of the chamber 50, and this on the one hand uncouples the motor MAO from the spindle 4 by disengaging the sector 63 from the lock 7, and, on the other hand, locks the spindle in the position 0,. A springloaded thrust pin I9, sliding in a guide integral with the wall 50, can then engage its tip in an opening formed in the top arm of the rocker 8 as shown in FIG 1.

The position of the slide 5 is determined by a motor MGR carried by a shoulder formed in the guide 66 and the shaft of which is coupled to the slide 5 through a screw-and-nut system 68.

A device of the mechanical type, as that provided in order to lock the spindle 4 in an angular position 8 0,, may be provided to lock the slide 5 in a position R=R,,. Preferably, this second locking mechanism will be substituted by a temporary servocontrol of the motor MAR. To this end, a conventional distance-sensing mechanism is provided, comprising two microswitches 25 and 26 located on a component 69 fixed to the cradle 3 and cooperating with a component carried by the screw of the screw-and-nut system 68. The conventional connections between the microswitches and the motor MAR have been shown in a highly schematical way.

In addition to its internal and external openings, the air-lock chamber comprises a duct 12 which connects it to the pumping circuit and which can be closed off by a puppet valve 13.

The puppet valve 13 is mounted on a spring-loaded thrust pin 60 which can slide in a guide 61 integral with the enclosure 50. A bellows 62 provides a seal between the guide 61 and the puppet valve 13.

The thrust pins 19, 20 and 60 are respectively controlled by the earns 16, 14 and 15 on a camshaft 56, preferably controlled by means of a motor 32, which, when the specimen is being analyzed (FIG. 1), produces the necessary positioning of the various moving elements.

In FIG. 2, where the various cams can be seen, the shaft is in a position in which the specimen is introduced into the airlock chamber.

In order to show how the system which has been described is operated in connection with a pumping circuit, a conventional pumping circuit has also been schematically illustrated in FIG. 2. This circuit comprising: a main line 21, to which the air-lock chamber 30 is connected through the line 12, an air intake connected to the line 21 through a valve 41', a vacuum gauge 42 in the line 21; an isolation valve 43; a trap 44; and a primary pump 45 which operates continuously.

The operation of the device will be described, assuming first that the specimen is in the analysis position'(FlG. l):

l. the lock 7 has been placed in position A;

the camshaft 56 is stopped in a first predetermined position; the thrust pin 20 is not opposite the end of the slide 55 and accordingly the latter has a position which is determined by the spring 58 (FIG. 1); the cam 15 is in a position such that the puppet valve 13 is closed; the cam 16 is in a position such that the lock 19 is not in contact with the component 8; the external port 9 of the air-lock chamber is closed; the valve 41 is closed and the valve 43 open. Through the medium of the motors MAO and MAR, and R can be varied around 0,, and R in order to analyze any desired zone of the specimen 2. When the operator subsequently desires to gain access to the specimen, he swings the lock 7 into the position B, thus bringing the right-hand part of the lever into the notch in the component 28. As described earlier, this uncouples the motor MA!) from the spindle 4 and places said spindle in the position 6,.

2a. The controlling of the motor MAR through the medium of the contacts 25 and 26 in order to position the slide in accordance with the precise value R=R,,, is set in operation;

2b. Thereafter the motor 32 is caused to rotate in a first direction.

3. This rotation of the camshaft 56 successively produces the following operations:

The cam 16 causes the lock 19 to engage in the opening in the component 8, thus securing the angular position of the spindle 4.

The axis of the stage is thus locked in alignment with the air-lock axis, and the slide 55 is aligned in extension of the thrust pin 20.

The cam 14 acts upon the thrust pin 20 so that the object E enters the air-lock chamber and the platform 1 seats against the edges of the internal opening thereof.

The cam 15 ceases to operate the thrust pin 60 and the puppet valve 13 exposes the opening ofthe line 12.

4. The camshaft is stopped in a second predetermined position, the valve 43 is closed and the valve 41 opened.

Air then flows into the line 21 and the airlock 30.

From this moment onwards, the operator has access to the specimen simply by opening the port 9 and he can replace it by another specimen. The port 9 is then closed again, and the camshaft again rotated.

5. The camshaft is stopped in a third predetermined position; the valve 41 is closed and the valve 43 opened so that pumping off starts in line 21.

6. The handling of the specimen being terminated and the port 9 closed, the lock 7 is then swung into position A by the operator and this couples the motor MAO to the spindle 4 again.

Go. The motor 32 is caused to rotate in the direction opposite to that in which it. previously rotated.

The cam 15 enables the thrust pin 60 to return and the puppet valve 13 to open again, so that the pumping operation can be completed.

The camshaft 56 is stopped in the aforementioned second predetermined position" and the pressure in the line 21 is checked by means of the gauge 42.

. if the vacuum is satisfactory, the camshaft 56 is again rotated.

The cam 15 closes the valve 13.

The cam 14 releases the slide 55.

The cam 16 returns the lock '19, thus releasing the rocker 8 and the spindle 4.

9. The camshaft 56 is stopped in the aforementioned first predetermined position," and the servocontrol of the motor MAR is put to an end.

The object-carrier can then be placed in the desired analysis position by means of the motors MAO and MAR.

The external port 9 of the air-lock chamber will advantageously be constituted by a viewing window making it possible, for example, to observe the specimen through the medium of an optical microscope illustrated in H6. 2.

it will now be shown very schematically-this being no part of the invention-tl1at by means of a few more components, the system may easily be associated with a suitable programmer so as to limit the manual operations which are required from the operator to the actuation of the lock 7 when he wants to get access to the specimen.

ln this case, a supplementary cam 17, shown in FIG. 2 may be mounted on the camshaft 56. This cam is also shown in H6. 4 which is a schematic view in the vertical plane passing through the axis zz; this cam operates three contactors 22, 23 and 24, which are respectively actuated by the camshaft in the aforementioned three predetermined angular positions. The arrow shown is HO. 4 corresponds to the second direction of rotation of the camshaft.

ln addition, another contactor 29 is provided in the support 28 and so arranged as to be operated by the lock 7 when the latter is pivoted into the position B.

The programmer 90 is connected to the motors 32 and MAR, and to the contactors 22, 23, 24, 25, 26 and 29. The corresponding connections are only represented in a very symbolical way; in H0. 1, by a line connecting block 90 to elements 25, 26, MAR, and 29; and in HQ. 4 by another line connecting block 90 to contactors 22,23 and 24.

In the same way the connections of the programmer 90 with the motor 32 and with the elements 41, 42 and 43 of the pumping circuit are shown only by a plurality oflines connecting the programmer to those elements.

The operation of the system is then as described above except that, taking into account the signals given by contactors 22, 23, 24, 25, 26 and 29 and by the gauge 42 to the programmer 90, and the orders given by the latter:

I. In the analysis condition, the immobilization of the camshaft 56 in its first predetermined position and the states (close or open) of the valves 41 and 43 are due to cam 17 actuating contact 22.

2. When the lock 7 is swung by the operator into position B, this also actuates the contactor 29, which actuation brings as a consequence steps (2a) and (2b).

4. The camshaft need not be stopped in the second predetermined position but the actuation of contactor 23 by cam 17 brings as a consequence the closing of valve 43 and the opening of valve 42.

5. This step is due to cam 17 actuating contactor 24.

6. When lock 7 is swung by the operator into position A, this also breaks the contact at 29 which brings as a consequence step (6a).

7. This step is due to cam 17 again actuating contactor 23.

8. This step is a consequence of a signal sent by gauge 42 to programmer 90 when the pressure is satisfactory.

9. This is due to cam' 17 again actuating contact 22.

I claim:

l. A device for the displacement and replacement of a specimen in a specimen chamber, said device comprising: a stage having a center part for supporting a specimen and a peripheral part; an air-lock chamber having a wall provided with an aperture having edges, said air-lock chamber communicating with said specimen chamber through said aperture; a

first mechanism giving to said stage 2 of freedom, in said specimen chamber, within a space portion allowing the analysis of various zones of a specimen fixed thereto, said first mechanism making it further possible to place said stage opposite said aperture in a predetermined position outside said space portion; and an auxiliary mechanism for imparting to said stage a translatory movement between said predetermined position and a further position in which said peripheral part of said stage abuts said edges of said aperture, whereby said aperture is obturated after a specimen fixed to said stage has penetrated into said air-lock chamber.

2. A device as claimed in claim I, wherein: said stage comprises a platform including said center part and said peripheral part, said peripheral part having a surface normal to a fixed axis and said edges of said aperture also having a surface normal to said fixed axis; said first mechanism is designed to give to said stage various angular positions relatively to said fixed axis through imparting to said stage a rotary movement about said fixed axis, and various radial positions relatively to said fixed axis through imparting to said stage a translatory movement perpendicular to said fixed axis, said predetermined position corresponding to a predetermined angular position and a predetermined radial position of said stage relatively to said fixed axis; and said translatory movement imparted by said auxiliary mechanism is parallel to said fixed axis. 

